It is well known that immobilization of a person may lead to pressure sores, nerve damage ("Saturday Night Palsy"), decubitus ulcers and other problems. These types of concerns are particularly apparent in the field of anesthesiology, wherein a patient cannot voluntarily move, often for hours on end. Even when a person is conscious, sometimes supports or bolsters are desired for comfort or to prevent strain.
This problem, however, also occurs in normal persons who are immobilized for extended periods, persons with spinal cord injuries, persons required to sleep in the lateral decubitus position for respiratory purposes or due to sleep apnea, or hospitalized persons. Further, persons with impaired upper extremity circulation or nerve damage, e.g., to the brachial plexus, may be more susceptible to compromise due to forces incurred by laying in the lateral decubitus position.
Pads, pillows, bolsters and cushions are known which may be used for elevating body portions, maintaining the body in a lateral or inclined position, and which attempt to comfortably distribute the body weight. These pads, pillows and cushions are not, however, specifically designed for supporting a person in a lateral decubitus position, are bulky in storage, and have shortcomings. For example, a generally flat pad has limited conformability, and thus may produce pressure sores or decubitus ulcers. Foam rubber formed supports may be very bulky for the required height to relieve pressure on a shoulder, and have limited compressibility for extended storage. Thus, pads and foam rubber supports of sufficient size to raise and support the patient and to evenly distribute the forces generally consume large volumes during storage, and are difficult to dispose of when contaminated. Further, a heavier or denser patient sinks deeper, while a lighter or less dense patient rides high on the pad, suggesting the need for manual adjustment by an attendant to assure proper placement. However, such pads tend to have predefined configuration and time-consuming to adjust. Such pads and foam rubber supports also have limited abilities to restrict patient rolling, and in fact may promote undesired rolling by raising the center of gravity too high without providing a suitable lateral restriction.
In several surgical procedures of the lower extremity, the patient is rotated somewhat to the side to gain access to the lateral aspect of the leg. This is generally accomplished by placing a bolster beneath the lower back or hip region to tilt the pelvis up, thereby enabling the leg to be rotated. As presently employed, this method does not allow the position of the patient to be adjusted intraoperatively. The patient must therefore be positioned exactly as desired, or in the best compromise position prior to surgery. Due to the sterile field proximate to the bolster, repositioning the patient on the bolster risks infection.
In obstetrics, it is desirable to lift a hip of a patient by between about 20-40.degree.. This inclination promotes uterine displacement, useful in all Cesarean sections and deliveries in the supine position. The uterus tends to compress the vena cava and/or aorta (the so-called aorto-caval compression syndrome), impairing blood flow to the fetus. This is usually minimized by placing the expectant mother in the left lateral position. During delivery with the mother's feet in stirrups or Cesarean section, the patient is placed on their back, requiring displacement of the uterus to the side. It is therefore known to place a bolster, usually formed from a bundle of sheets or a bag of intravenous fluid, under the side of the lower back and hip, to displace the uterus off the large vessels. When the baby is delivered, the bolster must be manually removed. If the displacement achieved by the bolster is later determined to be insufficient, there is no suitable means for adjustment.
It is also know to form pneumatic cushions using layers of polyvinyl chloride sheets, locally heated to fuse layers. These layers may form bladders or tensile members within bladders. Other types of pneumatic cushions using other materials and fabrication methods are known, for example, RF sealed polyurethane and nylon reinforced polyurethane. In these pneumatic cushions, a flexible wall of a bladder confines a gas space, generally having a uniform pressure, and therefore the bladder is inflated such the wall corresponds to this pressure. Where a sheet is fixed at two parallel edges, the center of the sheet will balloon outward with a cylindrical surface from a positive pressure in the gas space toward a lower pressure space. Two such sheets sealed at corresponding edges will thus assume a rounded, cylindrical form. A large bladder may be configured by forming tensile members within the bladder to locally restrain the expansion. Thus, grossly convex and piecewise concave shapes may be obtained using existing techniques.
In using pneumatic bladders devices to support a person, where sufficient pressure is provided in the bladder to assure a desired device configuration, without substantial or undue deformation due to the weight of the person, an uneven pressure may be applied to the skin of the person due to convex sections of the structure supporting the person. On the other hand, where the bladder pressure is low enough to allow uniform surface contact, the structural integrity may be impaired, and the inner walls of the bladder may locally contact each other or the structure may tend to roll. It is known to provide pneumatic bladder structures with separate inflation of multiple bladders, however these are often provided to separate bladders to provide increased safety of flotation devices or where gas spaces are not adjacent.
A known device, an Infusable.RTM. Disposable Pressure Infusor P/N IN-8000 available from Vital Signs, Inc., Totowa, N.J., includes a bladder formed of heat sealed polyvinyl chloride sheets, a pressure gage, a bulb pump, a vent valve and an inelastic bridging portion, for pressurizing an intravenous solution bag between one of the polyvinyl chloride sheets and the inelastic bridging portion.
U.S. Pat. No. 4,375,809 relates to an inflatable hand pillow for elevating the hand during healing. U.S. Pat. No. 5,012,539 relates to an inflatable medical support pillow for, e.g., elevating a body trunk or extremities. U.S. Pat. No. 5,418,991 relates to an inflatable structure for spacing legs, or supporting limbs, for example for immobilizing a leg. U.S. Pat. No. 3,897,777 relates to an inflatable head restraint. U.S. Pat. No. 4,139,920 relates to a body support designed to prevent decubitus ulcers. U.S. Pat. No. 5,070,559 relates to a pneumatic spinal support system having a plurality of types of bladders. U.S. Pat. No. 4,982,466 relates to an air mattress having controlled pressure to maintain subischemic conditions.
U.S. Pat. No. 4,265,232 relates to an inclined rigid arm support for stroke victims. U.S. Pat. No. 4,488,715 relates to an operating room rigid arm support having a foam padded interior surface. U.S. Pat. No. 3,939,829 relates to a foam restraining cuff. U.S. Pat. No. 3,678,926 relates to a stuffed support pillow for supporting a limb.
U.S. Pat. Nos. 3,790,975; 3,803,647; 3,813,716; 3,818,962; 3,822,425; 3,872,525; 3,949,438; 3,959,835; 3,984,595; 4,025,974; 4,042,988; 4,054,960; 4,371,999; 4,375,725; 4,394,784; 4,428,087; and 4,534,078 each relate to various air mattresses or structures auxiliary to air mattresses which are relevant to the background of this invention for implementing the structures disclosed herein.
Each of the patents cited herein is expressly incorporated herein by reference for its disclosure of aspects of the design, materials, manufacture and use of various pneumatic and support devices.